The perimeter of a triangle is 20 and the points (-2, -3) and (-2, 3) are two of the vertices of it. Then the locus of third vertex is :
a. (x-2)²/49 + y²/40 = 1
b. (x+2)²/49 + y²/40 = 1
c. (x+2)²/40 + y²/49 = 1
d. (x-2)²/40 + y²/49 = 1